You can see the two push buttons used to set each cat in or out should they run through an open door rather than the cat flap or evade the sensor in some way, as well as the Linksys WAP11 acting as a network bridge to link the system to the house WIFI network.

I've been pleased with the results so far. The RFID reader is mounted to the cat flap with velcro for now so I can move it to find the most reliable location. I think the magnet on the cat flap might not be helping the signal any, and I think I'll need to install the IR beams to counteract Bobbin just sticking her head through.